﻿using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Imaging;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Yitter.IdGenerator;

namespace tlBasic.Core 
{
    public class CaptchaHelper
    {
        /// <summary>
        /// 生成验证码图片
        /// </summary>
        /// <param name="length"></param>
        /// <returns></returns>
        public static CaptchaModel CreateCaptchaImage(int length = 4)
        {
            var rtnResult = new CaptchaModel();

            var code = GenerateRandom(length); // 随机字符串集合
            rtnResult.Code=code;
            rtnResult.CodeImageBase64 = "data:image/jpg;base64," + Convert.ToBase64String(Draw(code));
            rtnResult.Key = YitIdHelper.NextId().ToString();
            RedisHelper.SetString(AppStr.CaptchaKey + rtnResult.Key, code, new TimeSpan(0, 5, 0));         
            return rtnResult;
        }
        private static byte[] Draw(string code)
        {
            int codeW = 110;
            int codeH = 36;
            int fontSize = 22;

            // 颜色列表，用于验证码、噪线、噪点
            Color[] color = { Color.Black, Color.Red, Color.Blue, Color.Green, Color.Orange, Color.Brown, Color.Brown, Color.DarkBlue };
            // 字体列表，用于验证码
            string[] fonts = new[] { "Times New Roman", "Verdana", "Arial", "Gungsuh", "Impact" };

            using (var bmp = new Bitmap(codeW, codeH))
            using (var g = Graphics.FromImage(bmp))
            using (var ms = new MemoryStream())
            {
                g.Clear(Color.White);
                var rnd = new Random();
                // 画噪线
                for (int i = 0; i < 1; i++)
                {
                    int x1 = rnd.Next(codeW);
                    int y1 = rnd.Next(codeH);
                    int x2 = rnd.Next(codeW);
                    int y2 = rnd.Next(codeH);
                    var clr = color[rnd.Next(color.Length)];
                    g.DrawLine(new Pen(clr), x1, y1, x2, y2);
                }

                // 画验证码字符串
                string fnt;
                Font ft;
                for (int i = 0; i < code.Length; i++)
                {
                    fnt = fonts[rnd.Next(fonts.Length)];
                    ft = new Font(fnt, fontSize);
                    var clr = color[rnd.Next(color.Length)];
                    g.DrawString(code[i].ToString(), ft, new SolidBrush(clr), (float)i * 24 + 2, (float)0);
                }

                // 将验证码图片写入内存流
                bmp.Save(ms, ImageFormat.Png);
                return ms.ToArray();
            }
        }

        public static string GenerateRandom(int length)
        {
            var chars = new StringBuilder();
            // 验证码的字符集，去掉了一些容易混淆的字符
            char[] character = { '1','2', '3', '4', '5', '6', '7', '8', '9', '0' };
            Random rnd = new();
            // 生成验证码字符串
            for (int i = 0; i < length; i++)
            {
                chars.Append(character[rnd.Next(character.Length)]);
            }
            return chars.ToString();
        }
    }
    public class CaptchaModel
    {
        public string Code { get; set; }
        public string CodeImageBase64 { get; set; }
        public string Key { get; set; }
    }
}
